Equity (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended		6 Months Ended	12 Months Ended				1 Months Ended		3 Months Ended	1 Months Ended		4 Months Ended
	Apr. 02, 2013	Mar. 25, 2013	Jun. 30, 2013	Dec. 31, 2011 agreements	Jun. 30, 2013 2011 Repurchase Program [Member]	Jun. 30, 2013 First ASR Agreement [Member]	Jun. 30, 2013 Second ASR Agreement [Member]	Feb. 28, 2012 Uncollared ASR Agreement [Member]	Dec. 31, 2011 Uncollared ASR Agreement [Member]	Jun. 30, 2013 Uncollared ASR Agreement [Member]	Apr. 30, 2012 Capped ASR Agreement [Member]	Dec. 31, 2011 Capped ASR Agreement [Member]	Jul. 25, 2013 Subsequent Event [Member]
Equity (Textual) [Abstract]
Stock repurchase program number of shares authorized to be repurchased					50.0
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock					17.00%
Remaining shares available under repurchase program					8.3
Repurchase of additional shares		$ 500		$ 500
Repurchase of shares at a per share price						$ 250	$ 250
Shares received on initial delivery									5.0	7.2		5.0
Additional shares received	1.4							0.8			0.1		0.7
Accelerated Share Repurchases, Final Price Paid Per Share													$ 53.7995
Accelerated Share Repurchases, Cumulative Shares Repurchased													9.3
Accelerated Share Repurchase Program, Number of Agreements Entered				2
Interest In Joint Venture Minimum Percentage			20.00%
Business Acquisition, Agreement Terms, Change of Control, Put Option for Minority Interest Ownership, Effective Period			15 days